Mirrors on the market usually have three different coatings on the back: mercury, sterling silver and copper. Common mirror sizing after a period of time there will be speckled on the mirror, this situation should be the user used acid glass glue, and acid glass glue and usually the above material will react, resulting in speckled on the mirror. Therefore, we emphasize that neutral adhesives should be selected, which are divided into alcohol type and ketooxime type. If ketooxime type neutral adhesive is used in the copper mirror, ketooxime will slightly corrode the copper material. After a period of construction, traces of corrosion can be seen on the back of the sizing gel in the mirror. If alcohol type neutral adhesive is used, this phenomenon will not occur. The above is due to the diversity of the base material caused by improper material selection. Therefore, users are advised to do a compatibility test before using the gel, to see whether the gel is soluble in the material. Choose proper glass glue product to avoid unnecessary loss.